Wow... this really took off!
The discussion of whether or not hunting can be considered a "sport" is rather intriguing. I've wrestled with that myself. Is shooting from a tree a sport? Is using bates, decoys, calls, etc... sport? Interesting questions. I agree with Leatherneck about calling hunting a sport. I personally find immense joy in it. Look at me, here I am in July, taking time to participate in a conversation about it!! That speaks of my passion for it alone.
As for ethics, there are ethics in hunting. These ethics stem from responsibility. For instance, I often let more animals go than I shoot because the shot doesn't feel right. There may be only one small hole to shoot through or maybe the animal is a bit outside of a range that I feel comfortable shooting. To be ethical is to be responsible. It is respecting the animal's life and death. The overall ethical question of hunting is simple... life feeds off of life. Even green beans were once alive.
That all said, I think there are some practices that, though legal, seem unethical to me. Most obviously, to me, is baiting. It just doesn't seem right to put a stinky barrel out to draw in bears and take pot shots. Canned hunts over baits seem unethical. Trophy hunting is unethical. The notion of shooting an animal SOLELY for the size of its rack or beard, or weight seems wrong. Don't misunderstand me, I would love to have the opportunity to take a big buck or tom, but if I do, it should be the result of my work and luck, not the price I paid. It MUST be about the hunt, not the size of the dead animal at the end. It MUST be about the meat, not simply a head on wall.
So, I guess, I would say that the larger ethical question we all agree on: hunting is as natural as rain falling from the sky. That said, as Don Stokes said "Killing for thrills, just to see something die- now we're talking ethics." I would add, killing it for the thrill of its horns, beard, claws, skins, weight, or simply to be listed in some silly book that has a bunch of numbers in it, that's unethical.